This application provides fluidic devices, such as microfluidic devices, which can be used for the creation and/or manipulation of droplets in droplet-based microfluidic systems, as well as systems and methods for using the same. The microfluidic devices can be used to generate droplets, extract or inject volume to droplets, and/or split droplets. Also provided are methods for generating nucleosomes, and isolated DNA from nucleosomes (or from non-nucleosomes), for example using the disclosed devices.